Fuel injectors may be used to inject fuel from a fuel source into combustion engines. For example, fuel injectors may inject fuel directly into combustion chambers of an engine in what is known as direct injection or fuel injectors may inject fuel into an intake passage of an engine in what is known as port injection.
Fuel injectors have moving parts that control fuel flow through the injector. For example, a fuel injector may include a valve mechanism which engages with a valve mechanism seat to close off fuel delivery to an engine. A valve actuator, e.g., an electromagnetic valve actuator, may actuate the valve mechanism to lift it from the valve mechanism seat so that fuel may be delivered to the engine during fuel injection events.
However, the inventors herein have recognized that the moving parts in a fuel injector, such as those described above, may bounce against each other during motion. This bouncing may lead to degradation in components and operation of the fuel injector. For example, the bouncing may lead to fuel leaking through the injector causing fuel to drip into the engine. The dripped fuel may increase particulate matter (PM) formation during engine combustion, for example. Further, the leaking fuel is unmetered and may cause fueling control issues. The leaking fuel may also lead to deposit formation on the injector tip, thereby changing the injector flow transfer function and spray quality, for example. Further, due to the bouncing of the injector, there may be a limit on how quickly the injector can be opened for subsequent injections. Further still, the bouncing may increased injector tick noise and wear on injector components.
In one example approach to at least partially address these issues, a fuel injector comprises a valve mechanism and a valve mechanism seat, wherein at least one of the valve mechanism and the valve mechanism seat is permanently magnetized; an injector driver circuit for actuating the valve mechanism; and a spring biasing the valve mechanism in a closed position against the valve mechanism seat.
In this way, since at least one of the valve mechanism and the valve mechanism seat is permanently magnetized, a magnetic force may attract the valve mechanism to the valve mechanism seat which may reduce bouncing when the valve mechanism engages with the valve seat. This reduction in bouncing may reduce undesired residual fuel leaking when the injector is closed leading to a reduction in the formation of particulate matter and particulate emissions. Further, an accuracy of fuel metering may be increased due to a decrease in fuel leakage. For example, with reduced injector bounce, injector closing times may be reduced and injector response times may be increased. Further still, fuel velocity and inertia may be increased so that the time between subsequent injections may be reduced, which may, for example, increase split injection performance.
Further, if the valve mechanism is permanently magnetized, then the injector driver circuit may be operated in two modes depending on the direction of current supplied thereto. For example, a first amount of current may be supplied in a first direction to the injector driver to lift the permanently magnetized injector valve mechanism from the injector valve mechanism seat, and a second amount of current may be supplied in a second direction to the injector driver to close the permanently magnetized injector valve mechanism onto the injector valve mechanism seat.
In this way, for example, a polarity of the injector driver may be reversed to oppose the valve mechanism to seat attraction, thereby reducing the speed of the valve mechanism near closing and creating a soft landing effect. This may reduce tick noise and stress on fuel injector components. For example, initial spring forces on the valve mechanism and wear on a contact surface between the valve mechanism and the seat may be reduced.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.